This invention relates to protecting plastic pipe from impact damage, and more particularly to a crushable, impact-protective coating applied to the exterior of plastic pipe.
Fiber-reinforced plastic pipe, particularly that made from thermosetting resin reinforced with glass fibers, is widely used because of its resistance to corrosive liquids and its high strength. It is extensively used, for example, in the chemical, petroleum, and paper-making industries. In these industries, the pipe is frequently installed above ground. In underground applications it is most commonly used to convey either water or sewage.
One of the disadvantages of plastic pipes made from thermosetting resins is that such pipes are brittle and therefore crack easily even when subjected to a relatively moderate blow. In many of the above applications, such plastic pipes are subjected to the risk of receiving impact damage during shipping or installation. For example, impact damage often occurs when the pipe is loaded or unloaded from trucks. In above-ground installations, the pipe is commonly hoisted by cables, and can receive impact damage when striking a stationary object, such as a post. In underground installations, impact damage usually comes from rocks which fall onto the pipe in a trench before the trench is back-filled.